Lophophora williamsii, the "peyote" cactus, has a long history of use as a hallucinogen by the Indians of North America. It contains many alkaloids, but its hallucinogenic nature is due to the alkaloid, mescaline. The Indians have also utilized many other cacti in their folkloric medicine and have attributed stimulant and hallucinogenic properties to several other species which they also call "peyote". Little is known regarding the alkaloid content of many of these other cacti. Mescaline is not restricted to the Lophophora and has been detected in several South American Trichocereus species, e.g., the "San Pedro" cactus, T. pachanoi, which also have folkloric uses in Peru and Ecuador as hallucinogens. However, few reported efforts have been made to examine other species in these and closely related genera, especially species native to North America, for the presence of this hallucinogen and its analogues. Mescaline analogues, not found in L. williamsii, have recently been found in other cacti, e.g., macromerine and normacromerine from the "Dona Ana" cactus, Coryphantha macromeris, which is purportedly psychotropic. The existence in cacti of novel B-phenethylamine and tetrahydroisoquinoline alkaloids with hallucinogenic activity is a good possibility; yet, little phytochemical attention has been directed toward the isolation of such new cactus alkaloids. Certain lay publications are currently promoting various cacti as "natural and legal" psychedelics and provide their readers with dosages, methods of preparation and use, and the address of cactu leaders who unwittingly sell the plants for nonhorticultural purposes. The proposed research will attempt to isolate and characterize alkaloids from selected uninvestigated cacti by using the techniques of modern phytochemistry. The objectives will be to verify physiological activity in the various "peyote" cacti, to look for mescaline in domestic cacti that might become subject to abuse, and to search for new cactus alkaloids which might be psychotropic.